Production of fluids from a well is often assisted or achieved by operation of a downhole pump that forces fluids up toward the surface. Reciprocal drive downhole pumps are operated via a string of rods (sucker rods) that depend down into the well from the surface, where the string is reciprocated up and down along the axis of the wellbore by above-surface drive equipment. The most common conventional downhole reciprocal pump drive equipment configuration is the walking beam pump jack, which is often installed atop a concrete pad and may be further supported by piles, thus requiring significant preparation and resulting in notable ground disturbance.
Other prior art alternatives include hydraulic pump jacks that employ hydraulic cylinders bolted onto the wellhead to perform the required reciprocation of the pump rod string. However, shortcomings of such configurations may include lack of a smooth transition to the rod string between the up and down strokes, leaking fluids, and the potential of the hydraulic cylinders to rust because of oxidization and exposure to the elements.
Accordingly, there is a desire for a more efficient method to pump fluid without involving electrical/mechanical switches to change stroke direction or maintain stuffing box alignments. Such a solution would likely reduce premature stuffing box wear and hydraulic cylinder bearing wear as well as electrical/mechanical shut downs.